318 Build Up?

How much change would be involved in putting on the 302 heads? Those are the 85-91 pre-magnum heads, right? I read from an artical from Mopar Muscle (Sept. 2000) that they was able to get 215 rear wheel hp with a cam change and performer 4bbl. intake, but it was a '85 318 in a Dart. The valves were still stock 1.75/1.50 and no porting. Another article from a different Mopar Muscle (November 2003) in a stock 68 318 2bbl Cuda headers and 3" pipes, 305 TQ/ 317 HP. Could a 340 cam and headers with 3" exhaust be a good up grade using stock heads?